1. Field of the Invention
The present invention relates to a sample stage in the head of a scanning probe microscope, such as a scanning tunneling microscope (referred to as an STM hereinafter) or an atomic force microscope (referred to as an ATM hereinafter), and more particularly, to a sample stage capable of getting a sample plane to change direction by using a flexible shaft.
2. Description of the Related Art
STM head sample stages needed to coarsely focus on samples, heat sample planes and replace samples have been disclosed heretofore, for example, in the following documents:
1. M. Ringger, B. W. Corb., H. R. Hidber, R. Schlogl, R. Weisendanger, A. Stemmer, L. Rosenthaler, A. J. Brunner, P. C. Oelhafen and H. J. Gruntherodt: IBM J. Res. Develop., Vol. 30, No. 5, pp. 500-508, 1986. PA1 2. Th. Berghaus, H. Neddermeyer and St. Tosch: IBM J. Res. Develop., Vol. 30, No. 5, pp. 520-524, 1986. PA1 3. S. Chiang, R. J. Wilson, Ch. Gerber and V. M. Hallmark: J. Vac. Sci. Technol. A, Vol. 6, No. 2, pp.386-389, 1988. PA1 4. J. E. Demuth, R. J. Hamers, R. M. Tromp and M. E. Welland: J. Vac. Sci. Technol. A, Vol. 4, No. 3, pp. 1320-1323, 1986. PA1 5. M. Okano, K. Kajimura, S. Wakiyama, F. Sakai, W. Mizutani and M. Ono: J. Vac. Sci. Technol. A, Vol. 5, No. 6, pp. 1313-3320, 1987. PA1 6. H. Bando, H. Tokumoto, A. Zettl and K. Kajimura: Ultramicroscopy, No. 42-44, pp. 1627-1631, 1992.
A typical example of such conventional sample stages is illustrated in FIG. 28. This sample stage has a plurality of piezoelectric plates 52 supported by three legs 51 and a sample carrier 53 mounted on one of the piezoelectric plates 52. The legs 51 are made to move like a looper by applying driving voltage to the piezoelectric plates 52, thereby getting a sample plane 53a to change direction. FIG. 29A illustrates another conventional sample stage. This sample stage is provided with a running arm 55 pivotally mounted to a movable rod 56 by a connecting pin 54, and a sample carrier 58 is formed at one end of the running arm 55. On the side of the other end of the running arm 55, a stopper 57 is fixed to the sample stage. In this sample stage, the direction of a sample plane 58a is changed by linearly moving the movable rod 56 upward together with the connecting pin 54 from the state shown in FIG. 29A and pivoting one end of the running arm 55, at which the sample carrier 58 is mounted, upward about the stopper 57 in contact with the other end of the running arm 55, as shown in FIG. 29B.
However, the above-mentioned conventional sample stages have the following problems. Since the sample plane 53a is moved-by extending and contracting the plural piezoelectric plates 52 by the voltage application in the sample stage shown in FIG. 28, it takes a long time to change the direction of the sample plane 53a over a wide range. Furthermore, the method of applying the drive voltage to the plural piezoelectric plates 52 is complicated, and the directional change is unstable since the coefficient of friction of the bottom surface of each arm 51 is liable to change.
On the other hand, in the sample stage illustrated in FIG. 29, since the running arm 55 is mounted pivotally in a vertical plane by the connecting pin 54, the direction of the sample plane 58a can be also changed only in a vertical plane.